This application is related to a commonly assigned application having the title xe2x80x9cBattery Wire Lead Management,xe2x80x9d having an attorney docket number of 18133-065 and filed on Jan. 30, 2001, and the disclosure of this related application is hereby incorporated by reference
Embodiments of the present invention are directed towards an enclosure or chassis of a device, particularly an electronic device such as an uninterruptible power supply (UPS), for receiving the components of the device. The components typically contained within such an enclosure include printed circuit boards (PCBs), transformers, batteries, switches, and the like. The enclosure is used to house and hold the device components in a fixed, mechanically stable location. More particularly, embodiments of the present invention are directed towards a lightweight, inexpensive enclosure having a simplified assembly process and, in particular, to apparatuses, systems, and methods for providing a UPS housed in an integrated, lightweight, low-cost, and easily assembled package.
An uninterruptible power supply (UPS) is a type of power supply used to power and protect an electrical load that is sensitive to fluctuations in or the absence of electrical power. The UPS can be connected between the load and a source of electrical power, such as a mains power source or other commercially provided electric power. The UPS uses commercially supplied AC power to charge a DC battery and provide the AC power to load. Upon outages of power, the load draws its AC power from the DC battery through the DC to AC inverter. This isolates the load from power surges or brownouts and also furnishes a source of power during brief outages.
Commonly, a UPS comprises a rectifier, inverter, battery charger, DC battery, and other components, all housed within a single case or package. FIG. 1 shows a typical prior art UPS 1 used to provide regulated uninterrupted power. The UPS 1 includes an input filter/surge protector 2, a transfer switch 3, a controller 4, a battery 5, a battery charger 6, an inverter 7, and a DC-DC converter 8. The UPS also includes an input 9 for coupling to an AC power source and an outlet 10 for coupling to a load.
The UPS 1 operates as follows. The filter/surge protector 2 receives input AC power from the AC power source through the input 9, filters the input AC power and provides filtered AC power to the transfer switch 3 and the battery charger 6. The transfer switch 3 receives the AC power from the filter/surge protector 2 and also receives AC power from the inverter 7. The controller 4 determines whether the AC power available from the filter/surge protector is within predetermined tolerances, and if so, controls the transfer switch to provide the AC power from the filter/surge protector to the outlet 10. If the AC power from the rectifier is not within the predetermined tolerances, which may occur because of xe2x80x9cbrown out,xe2x80x9d xe2x80x9chigh line,xe2x80x9d or xe2x80x9cblack outxe2x80x9d conditions, or due to power surges, then the controller 4 controls the transfer switch 3 to provide the AC power from the inverter 7. The DC-DC converter 8 is an optional component that converts the output of the battery 5 to a voltage that is compatible with the inverter 7. Depending on the particular inverter 7 and battery 5 used the inverter 7 may be operatively coupled to the battery 5 either directly or through a DC-DC converter 8.
As consumer electronic products such as computers, become more widespread, smaller, lightweight, and less expensive, there has been a corresponding increase in the need for smaller, lighter, lower-cost UPS systems. However, designers of electronic instruments such as UPS""s typically have focused their energies on reducing the size and cost of the components contained within the device rather than redesigning the chassis or housing of the instrument. Thus, presently available UPS devices still take much time to assemble and require many connectors and fasteners that increase both weight and manufacturing cost. In addition, because parts such as batteries and transformers are heavy and awkward to install, it is difficult to design a simplified, lightweight UPS enclosure capable of securely containing such components.
Known enclosures and chassis designs for a UPS commonly include a metal frame having several partitions or walls to which the components are mounted or attached. The frame itself can be fastened to an outer device housing. Manufacturing the prior art chassis for a UPS is a relatively complicated and time-consuming process. For example, making a metal chassis often requires stamping and bending metal sheets. The surfaces of the sheets may be treated, for example by galvanizing, before connecting the sheets to each other by an appropriate connection method, such as screwing, welding, riveting, adhesives, or a combination of these methods. Components are connected to the chassis by fastening elements like screws or rivets or other connection techniques. Sometimes components are connected to the sheets before the sheets are assembled together.
It is also known to use hard plastic parts to form a chassis, but known plastic chassis designs nonetheless result in a complicated and time-consuming assembly process, because the fastening elements still must be attached to the chassis, for example by ultrasound welding, gluing, or pressing. Moreover, it is less common to use known plastic chassis designs for electronic devices such as UPS""s, which typically include very heavy components such as transformers and batteries. These heavy components (and even the relatively lighter components, such as printed circuit boards (PCBs). often require additional holding members, such as brackets or angle plates, to hold the component securely at the preferred position within the chassis. The holding members add to the weight, cost, and complexity of the chassis.
Thus, making a chassis for electronic instruments such as a UPS and assembling its components to it is costly and time-consuming, requiring the use of mounting tools, such as screw drivers, bending tools, riveting tools, welding tools, or adhesive dispensers. Metallic enclosures add an unnecessary amount of weight to the electronic instrument, but known plastic enclosures still require supporting members, if they are to be used with electronic instruments having particularly heavy components.
It is one object of the present invention to alleviate the aforementioned difficulties in assembly and manufacture of electronic instruments such as UPS devices by providing a UPS formed using mating panels of a sturdy, lightweight, substantially rigid material, such as ABS plastic, where the panels are fixedly mounted together to form a compact, user-friendly chassis using simple connection techniques that entail a minimum of tools and a minimal number of external fasteners.
In one general aspect, the invention provides an uninterruptible power supply for providing AC power to a load. The uninterruptible power supply comprises an input to receive AC power from an AC power source, an output that provides AC power. a DC voltage source that provides DC power, the DC voltage source having an energy storage device, an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power, a transfer switch constructed and arranged to select one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply, a chassis for housing at least the DC voltage source, inverter, and transfer switch. The chassis, in accordance with the invention, comprises a first panel having a substantially xe2x80x9cLxe2x80x9d shaped appearance, a second panel constructed and arranged to mate to the first panel; and a first fastener securing the first panel and the second panel into a substantially fixed configuration.
The chassis can be formed from a material such as plastic, semi-rigid polycarbonate (PC), Acrylonitrile-Butadiene-Styrene (ABS), ABS/PC, flame-retardant PC, ABS and ABS/PC products, polyvinyl chloride (PVC), polystyrene, high impact polystyrene (HIPS), polybutylene Terephthalate (PET), PC/PET, polybutylene terephthalate (PBT), PC/PBT, polyetherimide (PEI), acetal copolymer (POM), engineering thermoplastics (ETP), polyamides, expanded polypropylene (EPP), polyurethane, polyethylene, and metal.
The chassis, in one embodiment, also can comprise a third panel constructed and arranged to mate to the first panel and the second panel, wherein the first fastener is coupled to the third panel. The third panel can attach to the first panel using the first fastener and to the second panel using a second fastener.
At least one of the first and second panels can further include an integrally formed latch and the third panel can further include an integrally formed hook constructed and arranged to pivotably engage the latch. The input to the UPS can further comprise a line cord assembly constructed and arranged to mate with a line cord opening integrally formed into the third panel. The line cord assembly can further comprise an integrally formed strain relief element operably engaging the line cord opening. In addition, the line cord assembly can further comprise an integrally formed detent constructed and arranged to catch the line cord opening to keep the line cord assembly attached to the rear panel.
It is another object of the invention to provide a UPS chassis having integral preformed recesses capable of receiving and attaching electronic components therein, including heavy components such as transformers, using few, if any, fastening elements and simplified connection techniques, whereby the entire UPS can be assembled quickly and easily along a single axis of manufacture, using a minimum of tools.
In another general aspect, the invention provides an uninterruptible power supply for providing AC power to a load. The uninterruptible power supply comprises an input to receive AC power from an AC power source, an output that provides AC power a DC voltage source that provides DC power, the DC voltage source having an energy storage device, an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power, a transfer switch constructed and arranged to select one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply, a chassis for housing at least the DC voltage source, inverter, and transfer switch. The chassis, in accordance with the invention, comprises a first panel having a substantially xe2x80x9cLxe2x80x9d shaped appearance, a second panel constructed and arranged to mate to the first panel, and a first fastener securing the first panel and the second panel into a substantially fixed configuration, wherein at least one of the first and second panels comprises at least one integrated fastening element constructed and arranged to attach one or more components of the UPS to the chassis.
At least one of the first and second panels can further comprise an integrated fastener, such as a hook, constructed and arranged to attach a printed circuit board to the respective panel. At least one of the first panel and second panel can further includes at least one crush rib constructed and arranged to hold a component disposed adjacent to the crush rib, such as a transformer, in a substantially fixed position.
The second panel can further comprise an integrally formed compartment, which compartment can be constructed and arranged to enclose one or more UPS components, such as the energy storage device. The chassis can include a movable access panel providing access to the compartment. The movable access panel could be completely removed to permit installation or removal of one or more components, such as batteries, contained within the compartment.
It is another object of the invention to provide a method for constructing an uninterruptible power supply using a minimal number of tools and fasteners.
The foregoing and other objects, aspects, features, and advantages of the present invention will become more apparent from the following detailed description of the invention when viewed in conjunction with the accompanying drawings.